As a compressor, there has traditionally been a rotary compressor including a cylinder and a roller disposed inside the cylinder. In this rotary compressor, the roller is attached to a shaft that eccentrically rotates, and moves along the inner circumference surface of the cylinder with the rotation of the shaft.
In the rotary compressor, there is a minute gap between an end surface of a roller and an end plate member disposed to oppose this end surface, and between the outer circumference surface of the roller and the inner circumference surface of a cylinder, for the purpose of preventing seizure caused by sliding. The size of the gap is preferably as small as possible so as to prevent leakage of a refrigerant or lubricating oil. Even with such a gap however, the gap may close up and seizure may take place due to sliding, if the amount of thermal expansion of the roller is greater than that of the cylinder. Such a case may take place for example when the compressor is activated at a high speed.
Further, as a compressor other than the rotary compressor, there is a scroll compressor including a fixed scroll having a fixed-side wrap having a spiral shape, and a moveable scroll having a moveable-side wrap having a spiral shape that engages with the fixed-side wrap. In this scroll compressor, the moveable scroll is mounted to a shaft that eccentrically rotates, and circles with rotation of the moveable scroll.
In this scroll compressor, there is a small gap between an end surface of the wrap and a surface facing this end surface, and between a side surface of the wrap and a side surface (including a side surface of the other wrap) facing this side surface, for the purpose of preventing seizure caused by sliding. However, the gap closes up and seizure takes place, depending on the operation conditions.
To address the issue of seizure in the compressors, for example, Japanese Unexamined Patent Publication No. 275280/2006 (Tokukai 2006-275280) suggests a use of resin coating to improve the slidability. This allows prevention of seizure without enlarging the gap.